The present invention relates in general to the field of temperature control, and more particularly, to temperature control of microprocessors and integrated circuits during pre-delivery testing.
Microprocessors, and other integrated circuits, typically undergo a series of tests prior to delivery to ensure that they operate within certain design specifications, for example, specifications for environmental operating conditions. During such tests, the microprocessor generates heat and increases in temperature.
In order to prevent destruction of the microprocessor during testing, its temperature must remain below a maximum specified operating temperature. On the other hand, the microprocessor must be allowed to increase in temperature during testing to approximate actual operating conditions and insure error free operation during actual use. Therefore, the temperature of a microprocessor undergoing pre-delivery testing must be controlled according to a desired temperature profile.
Pre-delivery testing of a microprocessor typically requires operation of the microprocessor in a testing package of a design that is known to those in the field of microprocessor testing and manufacturing. Moreover, in order to facilitate mass production, it is desirable to test several microprocessors at one time by operating each in its own testing package under controlled environmental conditions in a parallel testing configuration.
Typically, such a known testing package comprises a socket for receiving the microprocessor, the socket also providing electrical connections to enable operation of the microprocessor by a given set of testing instructions passed to the microprocessor by testing software. Such a socket receives the microprocessor, which is then covered by a lid, the lid closes such that it secures the microprocessor within the socket. A thermocouple is typically provided on the lid, adjacent to the microprocessor, to enable sensing of the temperature of the microprocessor.
The testing package comprising the socket, microprocessor, lid, and thermocouple is then covered with a heat sink, which is placed in thermal contact with the lid and the underlying microprocessor. The heat sink most often includes exterior fins that facilitate convective heat transfer between the heat sink and the surrounding atmosphere, where heat transfer is aided by a controllable fan mounted in close proximity to the heat sink.
Temperature of the microprocessor is controlled in these prior testing packages by utilizing an active feedback system whereby the temperature of the microprocessor is monitored and controlled during testing. If the thermocouple of the testing package senses a temperature greater than the desired testing specification, an active feedback loop activates the controllable fan placed near the heat sink to effect cooling.
These prior systems for controlling the temperature of microprocessors undergoing pre-delivery testing tend to be relatively complex and costly. For each microprocessor being tested, these prior temperature control systems require a separate feedback loop including a thermocouple, a fan, a heat sink, and a corresponding logic circuit to provide active feedback loop control. Periodically, sensitive components of these systems must be calibrated, repaired, or replaced.
In these prior active feedback temperature control systems, delays or interruptions resulting from complex equipment set-up procedures, calibration, and repairs often diminish productivity and increase manufacturing costs, particularly when numerous microprocessors are tested in parallel.
Accordingly, it would be desirable to provide a simple and durable alternative to the present active feedback temperature control apparatus and methods that would allow efficient and low cost, parallel testing of numerous microprocessor or integrated circuits.
The present invention provides an apparatus and method for controlling the temperature of microprocessors during pre-delivery testing whereby a testing package, including a thermally conductive lid overlying and in thermal contact with the microprocessor, is covered by a block of thermally conductive material of predetermined thickness T, where T is a function of a desired temperature profile and, optionally, the current drawn by the microprocessor undergoing testing.
By selecting the thickness T of the block of thermally conductive material so that a desired microprocessor temperature profile maybe achieved, the present invention does not require active feedback temperature control, and thus does not require the complex, failure prone, or expensive equipment normally used in active feedback microprocessor testing procedures.
Because blocks of thermally conductive material are easily and inexpensively manufactured and configured for use in controlling temperature according to the present invention, large numbers of microprocessors may be tested in parallel at relatively low cost. In addition, because the blocks of thermally conductive material lack any moving parts or electrical connections, and are thus not prone to failure, large numbers of microprocessors may be tested without delays that might otherwise result from calibrating, repairing, or replacing components.
The foregoing has outlined the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood.
Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.